Linux Kernel up to 6.12.95/6.18.37/7.1.2 F2fs f2fs_recover_orphan_inodes entry_count out-of-bounds

Summaryinfo

A vulnerability identified as problematic has been detected in Linux Kernel up to 6.12.95/6.18.37/7.1.2. This vulnerability affects the function f2fs_recover_orphan_inodes of the component F2fs. This manipulation of the argument entry_count causes out-of-bounds. This vulnerability is registered as CVE-2026-63818. The attack needs to be launched locally. No exploit is available.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 6.12.95/6.18.37/7.1.2 and classified as problematic. Affected by this vulnerability is the function f2fs_recover_orphan_inodes of the component F2fs. The manipulation of the argument entry_count with an unknown input leads to a out-of-bounds vulnerability. The CWE definition for the vulnerability is CWE-125. The product reads data past the end, or before the beginning, of the intended buffer. As an impact it is known to affect availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: f2fs: validate orphan inode entry count f2fs_recover_orphan_inodes() trusts the orphan block entry_count when replaying orphan inodes from the checkpoint pack. A corrupted entry_count larger than F2FS_ORPHANS_PER_BLOCK makes the recovery loop read past the ino[] array and interpret footer or following data as inode numbers. On a crafted image, mounting an unpatched kernel can drive orphan recovery into f2fs_bug_on() and panic the kernel. Validate entry_count before consuming entries so corrupted checkpoint data fails the mount with -EFSCORRUPTED and requests fsck instead. Set ERROR_INCONSISTENT_ORPHAN as well, so the corruption reason can be recorded in the superblock s_errors[] field. This gives fsck a persistent hint even though mount-time orphan recovery failure may leave no chance to persist SBI_NEED_FSCK through a checkpoint.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2026-63818 since 07/19/2026. The exploitation appears to be easy. Attacking locally is a requirement. The exploitation requires an enhanced level of successful authentication. It demands that the victim is doing some kind of user interaction. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 6.12.96, 6.18.38, 7.1.3 or 7.2-rc1 eliminates this vulnerability.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.12.0
• 6.12.1
• 6.12.2
• 6.12.3
• 6.12.4
• 6.12.5
• 6.12.6
• 6.12.7
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• 6.12.89
• 6.12.90
• 6.12.91
• 6.12.92
• 6.12.93
• 6.12.94
• 6.12.95
• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
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• 6.18.11
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• 6.18.31
• 6.18.32
• 6.18.33
• 6.18.34
• 6.18.35
• 6.18.36
• 6.18.37
• 7.1.0
• 7.1.1
• 7.1.2

License

• open-source

Website

• Vendor: https://www.kernel.org/

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CPE 2.2info

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Entryinfo

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